Analytic evaluation and basis set dependence of intensities of infrared spectra

The infrared spectra of C60O isomers have been calculated through ab initio method. It has been observed that the simulated spectrum of one of C60O isomers is matching with the available experimental data in literature, while the other isomers are not matching so much. One can easily understand the basic physical properties of C60O by knowing of their vibration and geometric structures with their interrelation between these properties. It is found that the isomeric structures of C60O are very sensitive to electron correlation treatment with basis set that are employed. So the structure of C60O will not calculate from semi-empirical methods such as modified neglect of differential overlap (MNDO) or AM1 for more accuracy. The simulated spectra show different bands that rarely found all bands simultaneously in single experiment.

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Ab initio molecular orbital calculations of the infrared spectra of hydrogen bonded complexes of water, ammonia and hydroxylamine. I. Effect of choice of basis set on the predicted geometries and spectra of the monomers

Journal of Molecular Structure ◽

10.1016/0022-2860(86)80344-1 ◽

1986 ◽

Vol 141 ◽

pp. 331-340 ◽

Cited By ~ 25

Author(s):

G.A. Yeo ◽

T.A. Ford

Keyword(s):

Ab Initio ◽

Molecular Orbital ◽

Infrared Spectra ◽

Basis Set ◽

Molecular Orbital Calculations ◽

Bonded Complexes ◽

Hydrogen Bonded

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ChemInform Abstract: Vibrational Circular Dichroism and Infrared Spectra of 2-Methyloxirane and trans-2,3-Dimethyloxirane: Ab initio Vibronic Coupling Theory with the 6-31G*(0.3) Basis Set.

ChemInform ◽

10.1002/chin.199218030 ◽

2010 ◽

Vol 23 (18) ◽

pp. no-no

Author(s):

A. RAUK ◽

D. YANG

Keyword(s):

Circular Dichroism ◽

Ab Initio ◽

Infrared Spectra ◽

Vibronic Coupling ◽

Vibrational Circular Dichroism ◽

Basis Set ◽

Coupling Theory ◽

Circular Dichroïsm

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Theoretical Raman and Infrared Spectra for Amphetamine, Methamphetamine and 3,4-Methylenedioxymethamphetamine

Advanced Science Engineering and Medicine ◽

10.1166/asem.2020.2622 ◽

2020 ◽

Vol 12 (6) ◽

pp. 703-710

Author(s):

Leandro G. Silva ◽

Abel F. G. Neto ◽

José F. S. Costa ◽

Tais S. S. Pereira ◽

Mozaniel S. Oliveira ◽

...

Keyword(s):

Infrared Spectra ◽

Continuum Model ◽

Illicit Drugs ◽

Normal Modes ◽

Polarizable Continuum Model ◽

Program Package ◽

Basis Set ◽

Hybrid Functional ◽

Polarizable Continuum

Molecules used in the synthesis of illicit drugs, such as amphetamine, methamphetamine and 3,4-methylenedioxymethamphetamine which were studied in order to provide parameters to do their identification. Thus, Raman and Infrared spectra were calculated taking into account the polarizable continuum model and considering different solvents (water, toluene, acetone, chloroform and ethanol) at 298.15 K and 1 atm. The assignment of the normal modes of vibrations of these molecules was made. All calculations were carried out by quantum methods based on DFT with B3LYP hybrid functional and 6-311++g(d. p) basis set available in the Gaussian G03 program package. These informations can be helpful as a forensic data.

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Exploring the Ruthenium-Ligands Bond and Their Relative Properties at Different Computational Methods

Journal of Chemistry ◽

10.1155/2016/3672062 ◽

2016 ◽

Vol 2016 ◽

pp. 1-15 ◽

Cited By ~ 6

Author(s):

Adebayo A. Adeniyi ◽

Peter A. Ajibade

Keyword(s):

Thermodynamic Properties ◽

Computational Methods ◽

Infrared Spectra ◽

Computational Models ◽

Basis Set ◽

Functional Methods ◽

Light Atoms ◽

Geometrical Variation ◽

Homo Lumo

We report some experimental bond distances and computational models of six ruthenium bonds obtained from DFT to higher computational methods like MP2 and CCSD. The bonds distances, geometrical RMSD, and the thermodynamic properties of the models from different computational methods are similar. It is observed that optimization of molecules of many light atoms with different functional methods results in significant geometrical variation in the values and order of the computed properties. The values of the hyperpolarizabilities, HOMO, LUMO, and isotropic and anisotropic shielding are found to depend greatly on the type of the functional used and the geometrical variation rather than on the nature of basis set used. However, all the methods rated modelled Ru-S, Ru-Cl, and Ru-O bonds as having the highest hyperpolarizabilities values. The infrared spectra data obtained from the different computational methods are significantly different from each other except for MP2 and CCSD which are found to be very similar.

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